Syphilis is easily transmitted. The pathogens are present wherever the effected skin or mucous membranes secrete fluid, as well as in the blood.
The bacteria can then enter the body of another person via the tiniest cuts or injuries in the skin or mucous membranes (for example in the mouth, anal area, on the penis or in the vagina). This usually occurs during unprotected vaginal or anal sex. Syphilis can also be passed on during oral sex. It can also be very easily transmitted by sharing needles when using drugs. Pregnant women can pass the bacteria on to their unborn child.
People with no symptoms can still infect others.